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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Identidade na pluralidade: avaliação, produção e percepção linguística na cidade de São Paulo / Identity and diversity: linguistic evaluation, production, and perception in the city of Sao Paulo

Lívia Oushiro 20 February 2015 (has links)
Esta pesquisa apresenta análises sobre avaliação, produção e percepção linguística no português paulistano, por meio do exame de quatro variáveis sociolinguísticas: a realização de /e/ nasal como monotongo [e] ou ditongo [ej] (como em fazenda); a pronúncia de /r/ em coda silábica como tepe [R] ou retroflexo [õ] (como em porta); a concordância nominal de número (como em as casas/as casa); e a concordância verbal de primeira e de terceira pessoa do plural (como em nós fomos/nós foi, eles foram/eles foi). O objetivo central é analisar, em uma comunidade amplamente heterogênea de um ponto de vista sociodemográfico, as inter-relações entre a expressão de identidades sociais através de usos linguísticos e a possível influência dos significados sociais desses usos em processos de variação e mudança linguística. Para tanto, analisou-se qualitativa e quantitativamente uma amostra contemporânea do português paulistano, composta de 118 entrevistas sociolinguísticas com falantes nativos, à luz dos pressupostos teórico-metodológicos da Sociolinguística Variacionista (Labov, 2006 [1966], 2008 [1972]). Tais análises compreendem o encaixamento linguístico e social de cada variável, bem como seu encaixamento simultâneo na fala de cada indivíduo. Além disso, examinaram-se percepções sobre as variantes de (-r), com base na técnica de estímulos pareados (Lambert et al., 1960), a fim de melhor compreender os mecanismos subjacentes à associação de certos significados sociais ao emprego de diferentes formas linguísticas. Os resultados mostram que, embora as correlações entre as quatro variáveis sociolinguísticas e variáveis sociais sejam bastante semelhantes entre si (todas se correlacionam com o Sexo/Gênero, a Classe Social e o Nível de Escolaridade dos falantes), há diferentes tendências dentro da comunidade por exemplo, mudança em direção à variante ditongada [ej]; padrões divergentes quanto ao emprego de (-r) por parte de jovens de diferentes classes sociais; variação estável das concordâncias nominal e verbal em regiões periféricas e mudança em direção à variante padrão em regiões centrais. Para compreendê-los, o exame de seus significados sociais é fundamental. Argumenta-se que [ej] tem se difundido rápida e unidirecionalmente pelo fato de se constituir um marcador (Labov, 2008 [1972]) para paulistanos, que não revelam ter consciência da variável, tampouco apresentam um discurso metalinguístico sobre suas variantes. O forte favorecimento do retroflexo entre jovens de classes baixas foi desencadeado por uma reinterpretação de seu significado social como uma variante local e de prestígio, devido à presença maciça de migrantes do Norte/Nordeste, cuja variante fricativa é relativamente mais estigmatizada na comunidade. Ao mesmo tempo, ainda que o encaixamento social das concordâncias nominal e verbal seja bastante semelhante, a marca zero de concordância nominal (as casa) goza de maior vitalidade por indexicalizar significados como masculinidade, paulistanidade e morador da Mooca. Não obstante as diferentes tendências que se verificam na comunidade, os padrões de encaixamento das variáveis linguísticas se reproduzem sistematicamente na fala de cada indivíduo, o que permite caracterizar os paulistanos como uma única comunidade de fala (Labov, 2006 [1966]), que compartilha normas de produção e de avaliação linguística. De acordo com o teste de percepções, os moradores da cidade também são consistentes em suas reações subjetivas a variantes de (-r). Demonstra-se adicionalmente que a coesão dialetal é promovida não por amplas categorias sociais como Sexo/Gênero ou Faixas Etárias, mas pelo princípio mais fundamental de densidade de comunicação (Gumperz, 1971b,a). / This study examines linguistic evaluation, production, and perception in São Paulo Portuguese, through analyses of four sociolinguistic variables: the realization of nasal /e/ as a monophthong [e] or as a diphthong [ej] (as in fazenda farm); the realization of coda /r/ as a tap [R] or as a retroflex [õ] (as in porta door); nominal number agreement (as in as casas/as casa the houses); and first person plural and third person plural verb agreement (as in nós fomos/nós foi we went, eles foram/eles foi they went). The main goal is to investigate the inter-relation between the expression of social identities through language uses and the possible impact of social meanings on processes of language variation and change, in a highly diverse and heterogeneous community. Based on the theory and methods of Variationist Sociolinguistics (Labov, 2006 [1966], 2008 [1972]), each variables linguistic and social embedding, as well as their simultaneous embedding in individual speakers speech, were analyzed both qualitatively and quantitatively in 118 sociolinguistic interviews with native Paulistano speakers. In addition, perceptions on the variants of (-r) were examined through an experiment using the Matched Guise Technique (Lambert et al., 1960), aimed at describing the mechanisms underlying the association of certain social meanings with different language forms. The results show that, in spite of the similarity between the social embedding of the four variables (all of them are correlated with speakers sex/gender, social class, and level of education), there are different trends within the community for instance, change towards (e) diphthongization; divergent patterns regarding (-r) in the speech of younger speakers of different social classes; stable variation in nominal and verbal agreement in peripheral areas but change towards the prestige variant in central areas. The explanation for these patterns is related to the variants social meanings. It is argued that [ej] has spread rapidly and unidirectionally because it is a marker (Labov, 2008 [1972]) for Paulistanos, who are not aware of the variable and do not present an elaborate metalinguistic discourse on its variants. The fact that retroflex /r/ is strongly favored by working class youth may be attributed to a reinterpretation of its social meaning, due to the extensive presence of migrants from the Northern and Northeastern regions of the country, whose /r/ realization as a fricative is relatively more stigmatized in the community. At the same time, although nominal and verbal agreement are very similarly stratified, the nonstandard variant of the former (as casa the houses) exhibits greater vitality as it indexes masculinities and local identities with the city and with Mooca, one of its most traditional neighborhoods. Despite different trends by different social groups in the community, the embedding of the linguistic variables is systematically reproduced in each speakers speech, which allows for the characterization of São Paulo as a single speech community (Labov, 2006 [1966]) in that its native speakers share norms of use and evaluation of the variants. According to the perception test, the city inhabitants are also consistent in their subjective reactions to the variants of (-r). It is shown that such social cohesion is promoted not by census social categories such as sex/gender or age, but by the more fundamental principle of density of communication (Gumperz, 1971b,a).
12

Modelo Weibull modificado de longa duração

Oliveira, Cleyton Zanardo de 07 December 2011 (has links)
Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-08-09T15:24:44Z No. of bitstreams: 1 DissCZO.pdf: 1359694 bytes, checksum: 90de19ac8dc5ae4c2ad7e286ab945d9b (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-09T17:18:02Z (GMT) No. of bitstreams: 1 DissCZO.pdf: 1359694 bytes, checksum: 90de19ac8dc5ae4c2ad7e286ab945d9b (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-09T17:18:08Z (GMT) No. of bitstreams: 1 DissCZO.pdf: 1359694 bytes, checksum: 90de19ac8dc5ae4c2ad7e286ab945d9b (MD5) / Made available in DSpace on 2017-08-09T17:23:14Z (GMT). No. of bitstreams: 1 DissCZO.pdf: 1359694 bytes, checksum: 90de19ac8dc5ae4c2ad7e286ab945d9b (MD5) Previous issue date: 2011-12-07 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / When a group of patients is monitored until a pre-established date for observation of the recurrence time of an event, it is possible that, at the end of the monitoring period, a parcel of such group has not yet suffered the event of interest. When that happens, even if the period is extended, there is evidence that an appropriate model for the theoretical survival function of the time until the event occurs would be one model able to bear this kind of data. This class of long duration models will be defined because the form presented by the nonparametric estimation of hazard function in this type of study indicates that the model should be flexible to allow such function to be increasing, decreasing, constant or U-shaped. In this report, we present the long duration modified Weibull model (LDMW) as a proposal to contemplate the issues in the medicine area. The LDMW model has a flexible hazard curve, which enables adjustment when the hazard is decreasing, increasing, U-shaped, unimodal, initially decreasing and posteriorly unimodal and constant. The report also particularizes models already known in the literature that contemplate long duration, such as the long duration Weibull (LDW), long duration Exponential (LDE) and short duration models, such as the modified Weibull (MW), Weibull and Exponential. The simulations showed that the odds of coverage reach the nominal probability of 95% for moderately to big sized samples, that the LDMW p model parameters estimation is costless when compared to the MW and that the selection criteria of the AIC and BIC models are not adequate to discriminate the LDMW model adjustment when compared to the LDW model adjustment for small or moderately sized samples. The LDMW model and its particular cases were adjusted into two sets of real data considering the Classic and Bayesian Inference. The first data set is about the time until the seroreversion of children born from HIV-positive mothers and the second data set is about the recurrence time of breast cancer in women. / Quando um grupo de pacientes é seguido até uma data pré-estabelecida, para a observação do tempo até a ocorrência de um evento, pode acontecer que, na data de término do acompanhamento, uma parcela do grupo não tenha sofrido o evento de interesse. Quando ocorre, ainda que se estenda o prazo, existem indícios de que um modelo adequado para a função de sobrevivência teórica do tempo até a ocorrência do evento seja um modelo que comporte esse tipo de dados. Será definida essa classe de modelos de longa duração, pois a forma apresentada pela estimativa não paramétrica da função de risco, nesse tipo de estudo, indica que o modelo deve ser flexível no sentido de permitir que a função de risco seja uma função crescente, decrescente, constante ou em forma de U. Nesta dissertação, apresenta-se o modelo Weibull modificado de longa duração (WMLD) como proposta para contemplar os problemas na área médica. O modelo WMLD possui curva de risco flexível, possibilitando o ajuste quando há o risco decrescente, crescente, forma de U, unimodal, inicialmente decrescente e, posteriormente, descrevendo forma unimodal e constante. Particulariza modelos já conhecidos na literatura que contemplam a longa duração como o Weibull de longa duração (WLD), exponencial de longa duração (ELD) e modelos de curta duração, como Weibull modificado (WM), Weibull e exponencial. As simulações feitas mostraram que as probabilidades de cobertura atingem a probabilidade nominal de 95% para amostras moderadas a grandes, que não existe custo de estimação do parâmetro p do modelo WMLD, quando comparado com o WLD, e que os critérios de seleção de modelos AIC e BIC não são adequados para discriminar o ajuste do modelo WMLD comparado com o ajuste do modelo WLD, para tamanhos de amostras pequenos ou moderados. Ajustou-se o modelo WMLD e seus casos particulares em dois conjuntos de dados reais, considerando a inferência clássica e a bayesiana. O primeiro conjunto de dados trata-se do tempo até a sororreversão de crianças que nasceram de mães portadoras do vírus HIV e o segundo trata-se do tempo até a recidiva em mulheres com câncer de mama.
13

Analyse statistique de processus stochastiques : application sur des données d’orages / Inference for some stochastic processes : with application on thunderstorm data

Do, Van-Cuong 19 April 2019 (has links)
Les travaux présentés dans cette thèse concernent l'analyse statistique de cas particuliers du processus de Cox. Dans une première partie, nous proposons une synthèse des résultats existants sur le processus power-law (processus d'intensité puissance), synthèse qui ne peut être exhaustive étant donné la popularité de ce processus. Nous considérons une approche bayésienne pour l'inférence des paramètres de ce processus qui nous conduit à introduire et à étudier en détails une distribution que nous appelons loi H-B. Cette loi est une loi conjuguée. Nous proposons des stratégies d'élicitation des hyperparamètres et étudions le comportement des estimateurs de Bayes par des simulations. Dans un deuxième temps, nous étendons ces travaux au cas du processus d’intensité exponentielle (exponential-law process). De la même façon, nous définissons et étudions une loi conjuguée pour l'analyse bayésienne de ce dernier. Dans la dernière partie de la thèse, nous considérons un processus auto-excité qui intègre une covariable. Ce travail est motivé, à l'origine, par un problème de fiabilité qui concerne des données de défaillances de matériels exposés à des environnements sévères. Les résultats sont illustrés par des applications sur des données d'activités orageuses collectées dans deux départements français. Enfin, nous donnons quelques directions de travail et perspectives de futurs développements de l'ensemble de nos travaux. / The work presented in this PhD dissertation concerns the statistical analysis of some particular cases of the Cox process. In a first part, we study the power-law process (PLP). Since the literature for the PLP is abundant, we suggest a state-of-art for the process. We consider the classical approach and recall some important properties of the maximum likelihood estimators. Then we investigate a Bayesian approach with noninformative priors and conjugate priors considering different parametrizations and scenarios of prior guesses. That leads us to define a family of distributions that we name H-B distribution as the natural conjugate priors for the PLP. Bayesian analysis with the conjugate priors are conducted via a simulation study and an application on real data. In a second part, we study the exponential-law process (ELP). We review the maximum likelihood techniques. For Bayesian analysis of the ELP, we define conjugate priors: the modified- Gumbel distribution and Gamma-modified-Gumbel distribution. We conduct a simulation study to compare maximum likelihood estimates and Bayesian estimates. In the third part, we investigate self-exciting point processes and we integrate a power-law covariate model to this intensity of this process. A maximum likelihood procedure for the model is proposed and the Bayesian approach is suggested. Lastly, we present an application on thunderstorm data collected in two French regions. We consider a strategy to define a thunderstorm as a temporal process associated with the charges in a particular location. Some selected thunderstorms are analyzed. We propose a reduced maximum likelihood procedure to estimate the parameters of the Hawkes process. Then we fit some thunderstorms to the power-law covariate self-exciting point process taking into account the associated charges. In conclusion, we give some perspectives for further work.
14

Bandes de confiance par vraisemblance empirique : δ-méthode fonctionnelle et applications aux processus des événements récurrents / Building confidence bands using empirical likelihood methods : functional delta-method and recurrent event processes

Flesch, Alexis 12 July 2012 (has links)
Disposant d’un jeu de données sur des infections nosocomiales, nous utilisons des techniques de vraisemblance empirique pour construire des bandes de confiance pour certaines quantité d’intérêt. Cette étude nous amène à renforcer les outils déjà existants afin qu’ils s’adaptent à notre cadre. Nous présentons dans une première partie les outils mathématiques issus de la littérature que nous utilisons dans ce travail de thèse. Nous les appliquons ensuite à diverses situations et donnons de nouvelles démonstrations lorsque cela est nécessaire. Nous conduisons aussi des simulations et obtenons des résultats concrets concernant notre jeu de données. Enfin, nous détaillons les algorithmes utilisés. / The starting point of this thesis is a data set of nosocomial infectionsin an intensive care unit of a French hostipal. We focused our attention onbuilding confidence bands for some parameters of interest using empiricallikelihood techniques. In order to do so, we had to adapt and develop somealready existing methods so that they fit our setup.We begin by giving a state of the art of the different theories we use.We then apply them to different setups and demonstrate new results whenneeded. Finally, we conduct simulations and describe our algorithms.
15

Genetic and ecophysiological dissection of tolerance to drought and heat stress in bread wheat : from environmental characterization to QTL detection / Dissection génétique et écophysiologique de la tolérance au stress hydrique et thermique chez le blé tendre : de la caractérisation de l’environnement à la détection de QTL

Bouffier, Bruno 16 December 2014 (has links)
L’étude des rendements en blé a mis en évidence une stagnation apparue dans les années 1990, notamment en France, et principalement lié aux stress hydrique et thermique. Dans ce contexte, améliorer la tolérance du blé européen à ces stress est de première importance. Cette étude avait pour but d’étudier le déterminisme génétique de la tolérance à ces stress chez le blé. Pour ce faire, trois populations de blé tendre du CIMMYT combinant des caractères d’adaptation à ces stress ont été cultivées en conditions irriguée, sèche et stress thermique irriguée plusieurs années. Des caractères physiologiques et agronomiques ont été mesurés sur un réseau de 15 essais. Une méthodologie de caractérisation environnementale a été développée et a permis l’identification de six scenarii de stress au sein du réseau. Une covariable environnementale représentative de chacun a été extraite. L’utilisation des modèles de régression factorielles a permis la décomposition de l’interaction génotype x environnement ainsi que la mise en évidence d’une sensibilité différentielle au stress dans le germplasm. Une recherche de QTL multi-environnementale a conduit à la détection de régions génomiques contrôlant les caractères physiologiques et agronomiques ainsi que leurs interactions avec l’environnement. De la caractérisation environnementale à la détection de QTL, cette étude a abouti au développement d’un outil pour les sélectionneurs permettant l’évaluation du potentiel des génotypes face à une gamme d’environnement, mais aussi à l’identification de régions génomiques impliquées dans le contrôle de la tolérance aux stress hydrique et thermique chez le blé tendre. Ceci pourrait améliorer la tolérance à ces stress au sein du germplasm européen. / A stagnation of wheat yield was reported in France and other countries worldwide since the 1990’s, which incriminated mainly drought and heat stress. Improving the European wheat tolerance to them is of first importance. This study aimed to investigate the genetic determinism of the tolerance to such stresses. Three CIMMYT bread wheat populations combining complementary heat and drought adaptive habits were grown in Northern Mexico under irrigated, drought and heat-irrigated treatments from 2011 to 2013. The trial network comprised 15 trials and both physiological and agronomic traits were scored. First, an environmental characterization methodology was developed and resulted in the identification of six main environmental scenarios in the network. A representative environmental covariate was extracted from each of them. Then, a factorial regression model leaded to the dissection of the genotype-by-environment interaction and highlighted differential stress sensitivity of the germplasm. Finally, a multi-environmental QTL detection resulted in the discovery of genomic regions involved in the control of both physiological and agronomic traits and the study of their sensitivity to the environment. From the environmental characterization to the QTL detection, this study resulted in the development of a tool for breeders which may enable the evaluation of the potential of any genotypes in front of a range of environment, but also the identification of genomic regions involved in the control of the tolerance to drought and heat stress in bread wheat. This may help in improving the tolerance of the European bread wheat germplasm to drought and heat stress.
16

Les modèles de régression dynamique et leurs applications en analyse de survie et fiabilité / Dynamic regression models and their applications in survival and reliability analysis

Tran, Xuan Quang 26 September 2014 (has links)
Cette thèse a été conçu pour explorer les modèles dynamiques de régression, d’évaluer les inférences statistiques pour l’analyse des données de survie et de fiabilité. Ces modèles de régression dynamiques que nous avons considérés, y compris le modèle des hasards proportionnels paramétriques et celui de la vie accélérée avec les variables qui peut-être dépendent du temps. Nous avons discuté des problèmes suivants dans cette thèse.Nous avons présenté tout d’abord une statistique de test du chi-deux généraliséeY2nquiest adaptative pour les données de survie et fiabilité en présence de trois cas, complètes,censurées à droite et censurées à droite avec les covariables. Nous avons présenté en détailla forme pratique deY2nstatistique en analyse des données de survie. Ensuite, nous avons considéré deux modèles paramétriques très flexibles, d’évaluer les significations statistiques pour ces modèles proposées en utilisantY2nstatistique. Ces modèles incluent du modèle de vie accélérés (AFT) et celui de hasards proportionnels (PH) basés sur la distribution de Hypertabastic. Ces deux modèles sont proposés pour étudier la distribution de l’analyse de la duré de survie en comparaison avec d’autre modèles paramétriques. Nous avons validé ces modèles paramétriques en utilisantY2n. Les études de simulation ont été conçus.Dans le dernier chapitre, nous avons proposé les applications de ces modèles paramétriques à trois données de bio-médicale. Le premier a été fait les données étendues des temps de rémission des patients de leucémie aiguë qui ont été proposées par Freireich et al. sur la comparaison de deux groupes de traitement avec des informations supplémentaires sur les log du blanc du nombre de globules. Elle a montré que le modèle Hypertabastic AFT est un modèle précis pour ces données. Le second a été fait sur l’étude de tumeur cérébrale avec les patients de gliome malin, ont été proposées par Sauerbrei & Schumacher. Elle a montré que le meilleur modèle est Hypertabastic PH à l’ajout de cinq variables de signification. La troisième demande a été faite sur les données de Semenova & Bitukov, à concernant les patients de myélome multiple. Nous n’avons pas proposé un modèle exactement pour ces données. En raison de cela était les intersections de temps de survie.Par conséquent, nous vous conseillons d’utiliser un autre modèle dynamique que le modèle de la Simple Cross-Effect à installer ces données. / This thesis was designed to explore the dynamic regression models, assessing the sta-tistical inference for the survival and reliability data analysis. These dynamic regressionmodels that we have been considered including the parametric proportional hazards andaccelerated failure time models contain the possibly time-dependent covariates. We dis-cussed the following problems in this thesis.At first, we presented a generalized chi-squared test statisticsY2nthat is a convenient tofit the survival and reliability data analysis in presence of three cases: complete, censoredand censored with covariates. We described in detail the theory and the mechanism to usedofY2ntest statistic in the survival and reliability data analysis. Next, we considered theflexible parametric models, evaluating the statistical significance of them by usingY2nandlog-likelihood test statistics. These parametric models include the accelerated failure time(AFT) and a proportional hazards (PH) models based on the Hypertabastic distribution.These two models are proposed to investigate the distribution of the survival and reliabilitydata in comparison with some other parametric models. The simulation studies were de-signed, to demonstrate the asymptotically normally distributed of the maximum likelihood estimators of Hypertabastic’s parameter, to validate of the asymptotically property of Y2n test statistic for Hypertabastic distribution when the right censoring probability equal 0% and 20%.n the last chapter, we applied those two parametric models above to three scenes ofthe real-life data. The first one was done the data set given by Freireich et al. on thecomparison of two treatment groups with additional information about log white blood cellcount, to test the ability of a therapy to prolong the remission times of the acute leukemiapatients. It showed that Hypertabastic AFT model is an accurate model for this dataset.The second one was done on the brain tumour study with malignant glioma patients, givenby Sauerbrei & Schumacher. It showed that the best model is Hypertabastic PH onadding five significance covariates. The third application was done on the data set given by Semenova & Bitukov on the survival times of the multiple myeloma patients. We did not propose an exactly model for this dataset. Because of that was an existing oneintersection of survival times. We, therefore, suggest fitting other dynamic model as SimpleCross-Effect model for this dataset.

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